This invention relates generally to methods and apparatus for machining of components, such as gas turbine engine blades and vanes, which have complex contours.
Machining processes, such as grinding, for at least some known components discharge a coolant fluid toward the machining zone in sufficient quantity and velocity to avoid heat damage to the machined component. However, when a complex profile is being machined in a component it may be difficult to provide adequate coolant to the machining zone along the entire profile because fluid flow that exits the nozzle diverges rapidly and may have insufficient velocity to penetrate the machining zone. Moreover, certain machining operations, such as grinding, may be limited to lower wheel speeds during machining due to lack of adequate cooling flows.
The present invention overcomes these difficulties by using a coolant flow nozzle that has an exit aperture for ejecting a fluid jet with a selected cross-sectional shape to substantially match the contour of the component being machined. The fluid flow passage in the nozzle has a first portion having a first cross-sectional shape, and a second portion having a second cross-sectional shape, wherein the second cross-sectional shape is selected such that fluid discharged from the nozzle has a selected cross-sectional discharge pattern. The complex geometry of the fluid flow passage in the nozzle can be machined by using wire electro-discharge machine (“EDM”) techniques. The present invention facilitates providing enhanced cooling of the components with complex geometries during machining, leading to more accuracy and repeatability of the machining process. The present invention also enables higher machining speeds to be utilized without creating thermal damage to machined components, with longer tool life.